Multiunit electron tube



1w. w. EITEL Err AL MULTIUNIT ELECTRON'TUBE 2 Sheets-Sheet 1 Filed May 29, 1946 M 3 MLU W, m M @mmf o mms n M A M. MA ..K MMJ d July 29, 1947.

July 29, l947 w. w. EITEL Er Al. 2,424,635

MULTIUNIT ELECTRON TUBE K Filed May 29, 1946 2 Sheets-Sheet 2 K INVENToRs M -4 W/LL/AM W E/TEL.

Y JACK A. ME CUL ouf-5H Arm/@Nev Patented July 29, 1947 MULTIUNIT ELECTRGN TUBE William W. Eitel, Woodside, and J ack A. McCullough, Millbrae, Calif.,

assignors to Eitel- McCullough, Inc., San Bruno, Calif., a corporation of California Application May 29, 1946, Serial No. 672,988

6 Claims.

Our invention relates to electron tubes of the power or transmitting tube type, and more particularly to improvements in multi-unit tubes of the character disclosed in our copending application, Serial No. 645,441, iiled Feb. 4, 1946.

The trend in electron tube design is toward tubes capable of operation at the higher frequencies. It is not diiiicult to achieve the desired electrical properties for good operation at high frequencies with tubes of small physical size because small tubes have certain inherent advantages from the standpoint of tube structure and geometry, such as maintaining closer electrode spacings and lower inductance leads. The disadvantage of small structures for power tube uses is the limitation on power output due to lack of heat dissipation from the electrode, particularly from the anode. In other words, large physical size is incompatible with electrical properties required ior higher frequency operation, and this would appear to put a ceiling on power output for high lfrequency tubes.

The broad object of our invention is to provide a tube capable of large power output without sacriice of those electrical properties required for high frequency operation.

Another important object is to provide a tub structure which simplifies the manufacture of power tubes, and which enables a variety of tubes of different power ratings to be built, all from basic tube units made alike.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of our invention. It is to be understood that we do not limit ourselves to this disclosure of species of our invention, as we may adopt variant embodiments thereof within the scope of the claims.

Referring t the drawings:

Figure 1 is a vertical sectional View of a tube embodying the improvements of our invention; and

Figure 2 is a top View of the same. y

Figure 3 is a top view showing a modified cooler structure.

Figure 4 is a detail View showing another modied cooler construction.

In terms of broad inclusion, our electron tube comprises a plurality of connected tube units,

preferably disposed in a circle about an axis. Each unit comprises an envelope carrying an external electrode such as an anode, and a cooler structure is provided for the external electrodes. In one form of our invention the cooler structure is common to the electrodes, and in a modied form the cooler structure is sectional to provide an individual section for each electrode. In either case the cooler structure is arranged about the tube axis and forms a passage for cooling fluid extending axially of the tube, with fins on the cooler structure projecting into the passage. These iins are preferably disposed transversely of the axis so that cooling iiuid yfrom the passage "flows outwardly along the ns. Terminals are provided for the electrodes of the tube units, and these terminals are preferably common to electrodes, such as grids and cathodes, oi the several units. A member extending transversely of the axis serves to tie the units together and also functions as an electrode terminal.

In greater detail and referring to Figures l and 2 of the drawings, an electron tube embodying our invention comprises a plurality of tube units 2 arranged in a circle about a vertical axis. We show six units, but a greater or less number of units may be employed in the tube. The tube units illustrated are triodes, but it is understood that they may be of other types such as diodes or tetrodes. These units are complete tube units, independently constructed and evacuated.

The triode units illustrated each comprises an anode 3, control grid 4 and cathode t. Anodes 3 are oi the external anode type adapted for cooling by forced air or the like, and are connected to a cooler structure l which is arranged about the main axis of the tube.

Anodes 3 are preferably formed as portions of the envelopes of the tube units. The anodes illustrated comprise a tubular body of metal, such as copper, carrying an exhaust tubulation 9 at the top and a sealing flange il adjacent the bottom. Metallic tubulation .9 is pinched oli at tip l2 after evacuation of the envelope. Flange Il is sealed to a cylindrically-shaped envelope section i3 of vitreous material such as glass.

While we show tube units embodying substantially full external anodes, it is understood that the anodes may be of the internal-external type wherein the outwardly projecting portion of the anode functions largely as a heat conducting member. In any event the outwardly projecting portions of the anodes are connected to the cooler structure l, the extent to which the anodes project into the envelope being immaterial from the standpoint of our invention.

The internal electrodes 4 and 6 of each unit are preferably supported on the lower portion of the envelope. As illustrated, a vitreous disk I6 sealed to a metallic ring il provides a closure for the lower end of the envelope, ring Il being sealed to envelope section i3 so that this ring forms part of the envelope wall. Grid 4 which extends into anode 3 is supported by a metallic bracket I8 secured to ring IT so that this ring functions as a lead-in conductor for the grid. The cathode illustrated is a spiral filament secured to lead-in conductors i9 sealed to disk I6. While we show a ilamentary type of cathode, it is understood that an indirectly heated type may be employed.

Cooler structure l, which is adapted for cooling by a fluid such as forced air or the like, comprises a plurality of metallic ns 2l preferably extending transversely of the tube axis. In the construction shown in Figures 1 and 2, wherein the cooler structure is common to the anodes of the tube units, the fins 2l are in the shape of flat rings or disks lying in parallel spa-ced horizontal planes, the annular fins being connected by tubular metallic core pieces 22 arranged vertically in a circle for receiving anodes 3 of the units. The anodes are secured to core pieces 2-2 yby a fusible bonding material 23 such as cadmium solder. Being common to the several tube units 2, the cooler structure 'I also functions to mechanically tie the units together.

The ring-shaped'cooler structure above described forms a central passage 20 for the air stream indicated by arrows 3D. Transverse fins 2l project into this passage so that the air may flow outwardly along the n surfaces. In order to build up a back pressure within the cooler structure to aid in forcing the air outwardly, the lower ln 24 is provided with a smaller opening 25.

The lower portions of the tube units are tied together by a circular support member 26 extending transversely of the main axis. This member is preferably of metal and, in the tube las illustrated, also functions as a terminal member for the control grids of the several tube units. As shown in Figure l, the member 26 has a series of apertures arranged to receive the lower ends of the envelopes of the tube units, flanges .bordering the apertures being soldered or otherwise connected to envelope rings Il' so that member 26 provides a common grid terminal. A central opening 2l in member 26 allows some of the an` to pass downwardly'. This opening is preferably smaller than opening 25 so that some of the air is forced outwardly between the tube units to cool the envelopes.

A pair of cathode terminal rings 28 are supported below terminal 26 by insulating spacers 29. The lamentary cathodes are connected in parallel to rings 2B by flexible conductors 3l, so that heating current may be supplied :by suitable connections made to the terminal rings.

The transverse arrangement of the cooler ns 2l is an important feature of our invention because we have found such a cooler structure to be very erlicient from the standpoint of heat dissipation in a multi-unit tube of the character described.

Figure 3 shows a modified tube embodying our invention, wherein the cooler 'l is of sectional construction. In this case the iins 32 are pieshaped segments so that each tube unit carries a separate section of the cooler structure. The lower iin 33 which extends inwardlyv to form the restricted opening 25 is also of pie-shape to match the other fins. By this arrangement the cooler sections t together to make up a generally ring-shaped cooler structure similar to that rst described. The common cooler structure shown in Figures 1 and 2 has the advantage of providing additional means for tying the tube units together, while the sectional cooler structure is easier to assemble.

The horizontal arrangement of the ns has certain advantages as hereinbefore mentioned, and is preferred, but it is understood that other nn arrangements may be employed. For example, radial ns extending longitudinally of the anodes may be used, particularly in the case of the sectional construction where each tube unit carries its own cooler section.

Figure 4 shows a modiiied cooler structure in which horizontal fins 4| of the cooler are provided with integral flanges 42 interiitting to form a tubular core for receiving the anode 3. This structure is adaptable for use with either the common cooler shown in Figure l or the sectional cooler shown in Figure 3. The advantage is that the core is formed as an integral part of the ns, making unnecessary the use of separate core pieces 22.

We Claim:

l. A multi-unit electron tube comprising a plurality of tube units, each unit having a plurality of electrodes and an individual envelope, the upper part of the envelope constituting an external anode, a cooler structure embracing the anodes of the several tube units and plOVidng a direct electrical connection between said anodes, said cooler structure comprising parallel heat radiating fins, a base structure engaging the lower portions of the envelopes of the several tube units and providing a direct electrical connection between corresponding electrodes of each of said tube units, said cooler and base structures affording supporting connections between the tube units.

2. A multi-unit electron tube comprising a plurality of tube units disposed about a central axis, said tube units being rigidly connected together as a single structural body, each unit having a plurality of electrodes and an individual envelope, part of the envelope constituting an external anode, and cooling means comprising parallel heat radiating fins mounted on said anodes, said ns extending transversely of said axis and providing a central passage extending in the direction of said axis.

3. .A multi-unit electron tube as deiined in claim 2, in which the cooling means is formed of a plurality of separable sections, each section comprising a plurality of ns mounted on one only of said anodes.

external anode, and a cooler structure arranged about said axis, said structure having tubular sleeves mounted on said anodes, and heat radiating fins connecting said sleeves and extending transversely of said axis.

5. A multi-unit electro-n tube comprising a plurality of tube units disposed about a central axis, said tube units being rigidly connected together as a single structural body, each unit having a plurality of electrodes and an individual envelope, part of the envelope constituting an external anode, and a sectional cooler for said anodes, each section of said cooler Comprising a plurality of heat radiating fins mounted on one of said anodes, the fins of the several sections converging toward said axis.

6. A multi-unit electron tube comprising a plurality of tube units disposed about a central axis, said tube units being rigidly connected together as a single structural body, each unit having a plurality of electrodes and an individual envelope, part of the envelope constituting an external anode, and a sectional cooler for said WILLIAM W. EITEL. JACK A. MCCULLOUGH.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,170,653 Bushbeck Aug. 22, 1939 2,401,059 Eitel et al. May 28, 1946 1,437,498 De Forest Dec. 5, 1922 1,924,368 McCullough Aug. 29, 1933 

